The synergistic interplay between surface negative charges and functional groups in the carbon dot establish a strong Li-ion affinity, resulting in homogeneous Li deposition.

No abstract

Polycyclic aromatic hydrocarbons (PAHs) are key components of organic electronics. The electronic properties of these carbon‐rich materials can be controlled through doping with heteroatoms such as B and N, however, few convenient syntheses of BN‐doped PAHs have been reported. Described herein is the rationally designed, two‐step syntheses of previously unknown ixene and BN‐doped ixene (B2N2‐ixene), and their characterizations. Compared to ixene, B2N2‐ixene absorbs longer‐wavelength light and has a smaller electrochemical energy gap. In addition to its single‐crystal structure, scanning tunneling microscopy revealed that B2N2‐ixene adopts a nonplanar geometry on a Au(111) surface. The experimentally obtained electronic structure of B2N2‐ixene and the effect of BN‐doping were confirmed by DFT calculations. This synthesis enables the efficient and convenient construction of BN‐doped systems with extended π‐conjugation that can be used in versatile organic electronics applications.

A powerful synthetic protocol based on a molecularly engineered anchoring carbon platform (ACP) is reported to stabilize concentrated edge-hosted single-atom catalytic sites of M–N (M = Fe, Co, Ni, Cu) on carbon supports. Polymerization with l-cysteine as an additional organic precursor produces an ACP sheath around the carbon nanotube (CNT)–graphene (GR) hybrid support made of a small domain size with abundant edge sites and doped with sulfur. A few-minute-long microwave pyrolysis anchors strongly the single-atomic M–N moiety on the ACP while suppressing its agglomeration during the high-temperature synthesis and makes the ACP highly graphitized. As a typical example, the edge-hosted single-atomic catalytic sites in Fe–N/S-CNT–GR provide superior pH-independent oxygen reduction reaction (ORR) activity to previously reported Fe–N–C catalysts and commercial Pt/C while demonstrating oxygen evolution reaction (OER) activity in basic conditions similar to known state-of-the-art catalysts. In particular, the Fe–N/S-CNT–GR catalyst is much more stable than commercial Pt/C and Ir/C catalysts during ORR and OER in both base and acid solutions. Inferior stability is a common problem of this type of single-atom heterogeneous catalyst (SAC). An aqueous Zn–air battery with our Fe–N/S-CNT–GR catalyst operates as effectively as the device with the commercial Pt/C–Ir/C catalysts. We believe that our protocol based on the molecularly engineered ACP and microwave pyrolysis can provide a new concept to synthesize a new generation of durable SACs, which could have broad applications in electrochemical energy conversion and storage.